Experimental Study on Mechanical Properties of Microbially Modified Slag Based on CT Technology

Microbial Induced Calcium Carbonate Precipitation (MICP) can effectively improve the residual soil to improve the physical and mechanical properties and significantly enhance its compressive properties. In this paper, the mechanical properties and microstructural experimental studies were carried out on specimens with different binder concentrations filled with different rounds of binder using basic mechanical tests, CT scanning techniques and SEM. Getting to the conclusion: (1) The increase in the number of cement filling rounds can improve the compressive properties of slag, when the number of filling rounds increased from 0 to 4, the maximum increase in the compressive strength of the specimen was 31.63%. (2) With the increase of the number of filling rounds the porosity of the slag specimen decreased significantly, and when the specimen experienced two rounds of filling, the reduction of its porosity reached the maximum of 16.8%. (3) When the number of filling rounds is 4, the proportion of small-diameter pores and large-diameter pores are close to each other, and the pores of the specimen are more uniform, and the average fractal dimension is 0.85, which is 37.96% less than that of n=0, and the distribution of pores of the specimen is simpler; with the increase of the number of filling rounds, the increase of the diameter of the small pores and the decrease of the diameter of the large pores can increase the densification of the soil body. (4) When the number of filling rounds reaches 8, calcium carbonate crystals are generated in large quantities, wrapping the soil particles and cementing adjacent particles together, so that the loose soil is completely covered by calcium carbonate crystals to form a solidified body with a certain degree of strength, and enhance the stability of the soil microstructure.